1. Field of the Invention
The present invention relates to an optical lens system for taking image, and more particularly to a two-lens type optical lens system for taking image used in a mobile phone camera.
2. Description of the Prior Art
In recent years, with the popularity of mobile phone cameras, the length of such lens systems have been reduced continuously, and the sensor of a general digital camera is none other than CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor). Due to advances in semiconductor manufacturing, the pixel size of sensors has been reduced from the early 7.4 um to the current 1.75 um. Therefore, there's increasing demand for miniaturization of the lens system.
In consideration of aberration correction, a conventional mobile phone's lens assembly usually consists of three lens elements, one of the typical structures is the Triplet type. However, when the length of the lens assembly is reduced from 5 mm to less than 3 mm, less space is available for the optical system, making it difficult to incorporate three lens elements into the space of the optical system. Therefore, the lens elements must become thinner, causing poor uniformity if the lens is made from plastic injection molding.
The present invention mitigates and/or obviates the afore-mentioned disadvantages.